Method and apparatus for setting registration in a multicolor printing machine based on printing substrate grade

Abstract

A method and apparatus for setting registration in a multicolor printing machine for the digital production of color separations, the actions of setting up and combining color separations being controlled when printing substrates of a different grade are fed in, in order to correct registration setting. In the event of a change in the printing substrate grade, the influence of this change on registration can be compensated for optimally before the printing substrate ( 16 ) is fed to the printing process. When the printing substrate grade is changed, the influence of all the properties of the printing substrate ( 16 ) that are relevant to registration is taken into account directly as the change is implemented, by correction values ( 4, 4 ′, . . . ) for the printing substrate ( 16 ) that are available before printing is carried out.

What is claimed is:  
     
       1. A method of setting registration in a multicolor printing machine ( 1 ) having a number of individual printing units ( 8 ,  8 ′) and a respective number of exposure devices ( 2 ,  2 ′) for the digital production of color separations ( 3 ,  3 ′), and a registration control system which is based on the detection of registration marks ( 7 ,  7 ′) which are printed by said individual printing units ( 8 ,  8 ′), the actions of setting up and combining the color separations ( 3 ,  3 ′) being controlled when printing substrates ( 16 ) of a different grade are fed in, in order to correct the registration setting, wherein: when a printing substrate grade is changed, the influence of all the properties of said printing substrate ( 16 ) that are relevant to registration is taken into account directly as the change is implemented, by correction values ( 4 ,  4 ′) for said printing substrate ( 16 ) that are available before printing is carried out, before a change in the printing substrate grade can have any influence on the registration marks ( 7 ,  7 ′), such that retroactive influence of properties of said printing substrate ( 16 ) of printed pages ( 5 ) which have gone before but are still in the printing process on registration of a new printed page ( 5 ′) that is already in the printing process is taken into account. 
     
     
       2. The method as claimed in  claim 1 , wherein properties of printing substrates ( 16 ) are taken into account on the basis of stored data ( 6 ) for common printing substrate grades or those that are repeatedly used. 
     
     
       3. The method as claimed in  claim 2 , wherein a new grade of printing substrates ( 16 ) is identified by measuring properties of such printing substrate ( 16 ) before the latter is fed to the printing process. 
     
     
       4. The method as claimed in  claim 3 , wherein correction values ( 4 ,  4 ′) for various properties of printing substrates ( 16 ) are available as stored data ( 6 ′), and wherein these properties are determined and the correction values ( 4 ,  4 ′) resulting from these properties are taken into account. 
     
     
       5. The method as claimed in  claim 4 , wherein a new grade of printing substrates ( 16 ) is taken into account on the basis of a manual input. 
     
     
       6. The method as claimed in  claim 4 , wherein the correction values ( 4 ,  4 ′) for various printing substrates ( 16 ) are machine-specific values based on experience. 
     
     
       7. The method as claimed in  claim 1 , wherein a change in the printing substrate grade is taken into account by storing files ( 21 ) on printed pages ( 5 ,  5 ′) to be processed. 
     
     
       8. The method as claimed in  claim 1 , wherein said method is used to correct a registration control system which is based on detection of the positions of elements ( 9 ,  9 ′,  10 ,  10 ′;  11 ) that carry color separations and substrate, before a change in the printing substrate grade can have any influence on registration marks ( 7 ,  7 ′) positions of said elements ( 9 ,  9 ′,  10 ,  10 ′). 
     
     
       9. The method as claimed in  claim 1 , wherein further influences on registration resulting from a printed page change ( 5 ,  5 ′) are taken into account when setting registration. 
     
     
       10. The method as claimed in  claim 1 , wherein the toner profile of color separations ( 3 ,  3 ′) of printed pages ( 5 ,  5 ′) is taken into account. 
     
     
       11. Apparatus for a multicolor printing machine ( 1 ) having a number of individual printing units ( 8 ,  8 ′) and a respective number of exposure devices ( 2 ,  2 ′) for the digital production of color separations ( 3 ,  3 ′), at least one controller ( 12 , 12 ′), which controls registration by registration marks ( 7 ,  7 ′) printed by individual printing units ( 8 ,  8 ′) and detected by a registration sensor ( 18 ), performing a registration correction by controlling the actions of producing and combining color separations ( 3 ,  3 ′) when printing substrates ( 16 ) of a different grade are fed in, wherein: at least one controller ( 12 ,  12 ′;  15 ) is such that when a printing substrate grade is changed, the influence on registration of all the properties of the printing substrate ( 16 ) that are relevant to registration is taken into account directly as the change is implemented, by available correction values ( 4 ,  4 ′) for said printing substrate ( 16 ), taken into account before a change in the printing substrate grade can have any influence on registration marks ( 7 ,  7 ′), and the retroactive influence of the properties of the printing substrate ( 16 ) of printed pages ( 5 ) which have gone before but are still in the printing process on the registration of a new printed page ( 5 ′) that is already in the printing process is taken into account. 
     
     
       12. The apparatus as claimed in  claim 11 , further including at least one memory ( 13 ,  13 ′), which contains stored data ( 6 ) on correction values ( 4 ,  4 ′) of common printing substrate grades or those that are repeatedly used, said at least one controller ( 12 ,  12 ′) controlling the actions of setting up and combining color separations ( 3 ,  3 ′) on the basis of said stored data ( 6 ). 
     
     
       13. The apparatus as claimed in  claim 12 , further including an input device ( 14 ) via which the action of taking the correction values ( 4 ,  4 ′) into account can be activated manually. 
     
     
       14. The apparatus as claimed in  claim 12 , wherein correction values ( 4 ,  4 ′) contained in said at least one memory ( 13 ,  13 ′;  21 ′;  33 ,  33 ′) are machine-specific values based on experience. 
     
     
       15. The apparatus as claimed in  claim 11 , further including a memory ( 21 ′) to be loaded with data ( 21 ) on printed pages ( 5 ,  5 ′) to be processed, and said at least one controller ( 12 ,  12 ′) determines the necessary correction values ( 4 ,  4 ′) from said loaded data ( 21 ). 
     
     
       16. The apparatus as claimed in  claim 11 , further including a device ( 20 ) for measuring properties of printing substrates ( 16 ), and a new grade of printing substrates ( 16 ) is identified by said at least one controller ( 12 ,  12 ′;  15 ) by said properties. 
     
     
       17. The apparatus as claimed in  claim 11 , further including at least one memory ( 33 ,  33 ′), which is loaded with data ( 6 ′) for various properties of printing substrates ( 16 ), a device ( 20 ) for measuring properties of printing substrates ( 16 ), and said at least one controller ( 12 ,  12 ′;  15 ) uses the correction values ( 4 ′) that result from said properties as a basis for setting registration. 
     
     
       18. The apparatus as claimed in  claim 11 , wherein said at least one controller ( 12 ,  12 ′) is such that it controls registration by detecting the positions of elements ( 9 ,  9 ′;  10 ,  10 ′;  11 ) of said printing machine ( 1 ) that carry color separations and substrates by position detecting elements ( 19 ), and takes correction values ( 4 ,  4 ′) into account before a change in the printing substrate grade can have any influence on such positions of said printing machine elements ( 9 ,  9 ′;  10 ,  10 ′;  11 ). 
     
     
       19. The apparatus as claimed in  claim 11 , wherein said at least one controller ( 12 ,  12 ′) is such that it takes into account further influences on registration resulting from a printed page change ( 5 ,  5 ′) when setting registration. 
     
     
       20. The apparatus as claimed in  claim 11 , wherein said at least one controller ( 12 ,  12 ′) is such that it takes into account toner profile of color separations ( 3 ,  3 ′) of printed pages ( 5 ,  5 ′).